Notably it’s before the data migration of 1.28 which changed the locations of game files, and it doesn’t auto update to Reforged like 1.31 did for so many people.

It’s the most “pure” version since the classic team started updating the game and therefore has the least amount of changes and bugs. As a few others have said I like 1.27, at least for single player where map size limits aren’t of concern.